2003 Chevy Cavalier Engine is running hot

I have replaced the thermostat 2 times, thinking I just had a bad one. Replaced the water pump, and the radiator. Yes, the cooling fan comes on and goes off like it is supposed to. There is no visible water leaking from anywhere other than the back flow valve on the resivoir. After a short time of running the top (left) hose is hot, the bottom (right) hose is still cold. (Like the water is not really circulating through the motor.) Out of options. What now?
Oh yeah! My heater inside the car does not work now. The air conditioner is still blowing cold air, just not the heater.